Apparatus for determining the position of aircraft not visible with the naked eye



March 21, 1933. J. SCI-HER 'ET AL APPARATUS FOR DET THE PbsrrIoN OF TPE NAKED EYE ERMINING AIRCRAFT NOT VISIBLE WITH Filed Nov. 15, 1924 2 Sheets-Sheet l C fiP/f) SCHIER 2 ShetseSfieet 2 ay w m/ w 5 M m a u a, A A? 0 m w ,5 E a, w J w E A 3 MW MAW w 5W Patented Mar. 21, 1933 comparatively short time, an aircraft UNHTED STATES PATENT OFFICE SLOVAKIA ArrARA'rus FOR, DETERMINING THE Posrrron or AIRCRAFT NOT/VISIBLE WITH THE NAKED EYE Application filed November 15,1924, Serial No. 750,215, and in flzechoslovakianovember 16, 1923.

Experience'teaches that it is very difficult and in fact almost impossible to detect an aircraft flying high in the air at night by means of the pencil of light from a reflector, without the'aid of suitable means. Even with the aid of the known acoustic direction detectors and other acoustic ap aratus by which thedirection of the aircra from the observer may be roughly estimated by the observer from merely subjective impressions, it takes a long time before the light of the reflector canbe thrown on the aircraft, if this be possible at all.

' The object of the present invention is to provide an apparatus permitting findin in a y in the air and not visible with the naked eye, more particularly at night time, by means of the light projected by optical device.

The essence of the invention consists in that sound receivers held during a predetermined period of observation with their acoustic axis in thedirection of the sound actuate an indicating device which indicates the angle (roof-angle) of the plane (roof'plane) passing through the point of observation and the horizontal .element aircraft, as well as the angle (course angle) between the intersection of the plane with the horizon and some given direction in a horizontal plane and these data are utilized for adjusting a device (reflector, telescope or the like) in the said plane (roof plane).

By this method it is possible to account for the speed of the aircraft, which is considerable as compared with the speed of the propagation of sound, by holding the reflector properly ahead of the acoustic line to the aircraft in the plane through the point of observation and the horizontal trajectory of the aircraft, which plane is called herein the roof plane which makes the roof angle with the horizontal, and the intersection of which roof plane with the horizontal plane makes the course angle with any given direction (for instancethe north south direction) I If now according to the invention the latter angle is adjusted on the horizontal circular scale of a horizontally rotatable refleca reflector or any other of the trajectory of the tor suspended in gimbals and the roof angle is adjusted on the vertical circular scale of the outer gimbal axis of a gimbal ring carrying the reflector, then the inner gimbal axiswhich is at right angles to the outer gimbal axis is also at right angles to the said roof plane so that the optical axis of the reflector which is at right angles to the inner gimbal axis is permanently in the roof plane when the reflector is turned round the inner gimbal axis, and therefore must pass through the aircraft in such plane.

e means by which the acoustic line of direction extending the invention of a double binaural device.

The annexed drawings show one embodiment of the invention by way of example.

Fig. 1 is a diagrammatic illustration of the theoretical basis of the method for determinng the course angle and the roof angle at any instant of the horizontal rectilinear flight.

Fig. showsa constructional form of the mechanical arrangement required therefor, in side elevation, partly in section. V

Fig. 3 sl1ows the same, arrangement in front elevation, partly in section.

Fig. 4 shows the same arrangement in plan new.

In Fig. 1 A B is the horizontal rectilinear path through which the aircraft flies in a given period of time. A, B, is the projection thereof on the horizon of the point of observation C and therefore A A =B B =:v, the height of the path of flight. The plane passing through the path A B and the point of observation called roof plane is inclined-to the horizon intersection of the roof plane with the horizontal plane is parallel to the projection A B and makes an angle K with any desired zero line, for-instance with the north southv direction 8 C N. In order to practically determine these two angles, assume that the two triangles A B (l/A -B O are mechanically reproduced at any reduced scales by mechanica-lly fixing at any desired but constant height it above the horizon passing through the point of observation 0, a point a, and adjusting it into the direction A C. This ad- 9 and carries by means of justment is efiected by craft by simultaneously moving the roda tangentially and radially. I If now on the surface of the map table, adapted to turn round a vertical axis and serving as the plane of projection, a series of arallel lines is drawn at suitable distances romeach other, it will always be possible to so turn the table that on adjusting the point a in the line to the target, the bottom end 0 is constantly on one of the parallel course direction lines or moves parallel thereto. From the distance 6 of this line from the axis of the table and the selected length 71- of the rod a a, the roof angle is found.

d=arc.tam.

I In order to permit the roof angle be rapidly determined the course direction lines are drawn on the surface of the table at such distances 0=cot d from the asis of the table that the geometrical locus of the projections of the point a is numbered correspondingly to the values of the roof angles by degrees while the course direction angles can be rea on the peri hery of the table from a selected zero point y means of a pointer on the pivot of the stand.

The mechanical apparatus resulting from this theoretical basis is seen in Figs. 2 to 4. On the pivotl of the stand 2 is loosely mounted the hub of a map table 3, horizontally ro tatable, the periphery of which is provided with bevel teeth 4 and a scale 5 the azimuth an les. A bevel pinion 6 engages in the vel teeth, the shaft 7 of =wh1ch is 'journaled in a frame .8 and may be rotated by a handle 9. The frame '8 is likewise loosely mounted on the vertical pivot of the stand by its hub 10 and carries by means of two hangers 11 a radial horizontal shaft 12 carrying on its outer en a handle 13, by the operation of which the bevel wheel 14 can be rotated, which latter is mounted on the inner end of said shaft. As the latter pinion engages in a ring 0 bevel teeth 15 secured to the stand 2, the frame 8 is rotated horizontally by the revolution y a ointer 17, I ta le can-be of the bevel wheel 14. Between the hub of said frame and .that of the ma 16 is secured to the pivot whic. ring carries whereby the azimuth of the map read on the ripheral scale 5.

V The yoke '18 extending diametrically above d 22 P t ng in the map table is itself constructed as a frame the two bearin s 19 along diametrically arranged tube'20 a apted to turn round its horizontal axis, which as the an uthal directionbasis,

ends the two microphones 21 the same direction. Be-

tube serving carries at'its two which the sound comes or 1 guided diametric for gu f the naked eye,

table, a ring arran ed which is carried by 25 an adapted to rotate in as an acoustic the tube 26 carries at its two a circular hub a vertical plane basis for the altitude direction,

ends the two m1 crophones 23, 24 pointing in the same direction. Thus the four microphones constitute two binaural sound receiving devices in a plane parallel to the acoustic base plane 26) and therefor give the incoming sound waves,

direction from the direction of the whenever the plane of these sound receivingdevices is properly adjusted, as is well known, incoming sound waves being the acoustic base plane 20,

horizontal supporting tube 20 the direction of the perpendicular to 26. Now on the the two rules 27 are secured which are provided at their inner edges with longitudinal are at right angles to the zontal bore for a pin,

into each 0 grooves and which ase plane (20, 26) and are connected at their top -tie 28 to form arigid frame.

of these ed a sliding prism 29 provided ends by a cross In each 'of the rules is mountwith a horif which bores engages a lateral pin 30 of a verticalrod 31}.

This r d, having a point at i held n a prismatic sliding piece ally with relation to the table by means of the inner grooves o yoke 18 and is provided with a female thread i into which enga nalled in the yo ts bottom end, is 32 which is map f the spindle 33 joure 18 and adapted to be rotated by the handle 34. Thus such rotab tion the vertical rod 31 is moved parallel to itself radially withrelation ide rules 27 is rought to the map table whereby a change of the inclination of the about, and thus also the microphone carrying tube 20 is turned round its horizontal axis and in this way a change of the altitude efiected.

direction base 26 is The acoustic azimuth of the aircraft is given by a horizontal line perpendicular ,to

the tube 20 and thus may be readily read on d the circle 5.

What we claim is: In an apparatus lowing for determining and folthe path of an object not visible but producin said object moving substanta y m with a sound, the

' a straight horizontal, line, a unitary structure located at the point of observation double binaural device for and comprising a determining the direction of the incoming sound waves, means cooperating with the said binaural device for keeping the plane of the sound receiving orifices of the said binaural device perpendicular to the said incoming sound waves movlng 1n the so-called roof plane,

ed with parallel hn and a horizontal rotatable table for plotting a line arallel toj aircra ,the said es,'the

the said lines from the center of to the cotangent angle having of the an? e of the roof plane relatively to a horizonta plane, and means on said firstmentioned means and cooperating with said table for defining a rectangular rotatable tria constant height-and a hypothenuse. of varlable length, the said hypothenuse being arranged at a rightangle to the binaural' device whereb the said hypothenuse lies constantly in the direction of the sound waves.

In testlmony whereof we have aflixed our signatures.

JOHANN SCHIER. L PETSCHENIG. ANTON PEINL. 

